中文
含义
F21 为电机故障。洗衣机主驱动电机或其测速反馈系统异常，控制器无法准确获取电机转速信号或检测到电机运行状态异常，程序中断并显示故障代码，防止电机或驱动模块进一步损坏。
常见原因
- 电机碳刷磨损殆尽（适用于串激电机机型），碳刷与换向器接触不良导致电机无法正常启转。
- 测速发电机（转速传感器/霍尔传感器）故障，控制器无法接收到转速反馈信号。
- 电机驱动模块（变频板）损坏，无法输出正确的驱动电压或电流。
- 电机绕组短路、断路或对地绝缘失效。
- 电机线束接头松动、氧化或线束内部断裂，造成信号或供电中断。
自助排查
- 断开电源，等待 5 分钟后重新上电，尝试运行一个短脱水程序，观察故障是否复现。偶发性故障可能与电网干扰有关。
- 若机器为使用多年的串激电机机型，碳刷可能已到使用寿命，电机转动无力或有异响。需要更换碳刷或电机总成，此项操作需由专业人员执行。
- 检查是否存在洗涤过载（放入衣物量远超额定容量），过载可能导致电机堵转触发故障。
- 空桶状态下单独运行脱水程序，若能正常运转，说明电机基本完好，此前故障可能是负载引起的瞬时保护。
- 若空桶运行仍报 F21，电机或其驱动系统存在硬件故障，请联系西门子售后服务中心安排检修，勿自行拆修。
English
Meaning
F21 indicates a motor fault. The main drive motor or its speed feedback system is abnormal — the controller cannot accurately read the motor speed signal or detects an irregular motor operating state. The program is interrupted and the fault code is displayed to prevent further damage to the motor or drive module.
Common Causes
- Motor carbon brushes are completely worn (on universal-motor models), resulting in poor contact between brushes and commutator and preventing the motor from starting properly.
- Tachogenerator (speed sensor / Hall sensor) failure — the controller cannot receive a speed feedback signal.
- Motor drive module (inverter board) is damaged and unable to output the correct drive voltage or current.
- Motor winding short circuit, open circuit, or insulation breakdown to ground.
- Motor wiring harness connector is loose, oxidized, or has an internal wire break, causing signal or power interruption.
Self-Check Steps
- Disconnect the power, wait 5 minutes, then reconnect and attempt to run a short spin cycle to see if the fault recurs. An occasional fault may be related to grid interference.
- If the machine is a universal-motor model that has been in service for many years, the carbon brushes may have reached their service life — the motor may sound weak or produce unusual noises. Carbon brush or motor assembly replacement requires a qualified technician.
- Check for laundry overload (far exceeding the rated capacity), as an overloaded drum can stall the motor and trigger the fault.
- Run a spin-only cycle with an empty drum. If the cycle completes normally, the motor is likely in good condition and the previous fault may have been a transient overload protection trip.
- If F21 persists even with an empty drum, the motor or its drive system has a hardware fault. Contact Siemens after-sales service for diagnosis — do not attempt to disassemble or repair yourself.